WO2017110959A1 - User terminal, wireless base station, and wireless communication method - Google Patents

Abstract

The present invention enables communication to be performed by using an uplink shared channel that has a configuration suitable for short TTIs. A user terminal according to the present invention sets short TTIs so as to include one of two symbols in which demodulation reference signals for a normal-TTI uplink shared channel are transmitted. In the short TTIs, the user terminal transmits the uplink shared channel and transmits a demodulation reference signal for the short-TTI uplink shared channel in the one symbol.

Description

User terminal, radio base station, and radio communication method

The present invention relates to a user terminal, a radio base station, and a radio communication method in a next-generation mobile communication system.

In the UMTS (Universal Mobile Telecommunications System) network, Long Term Evolution (LTE) has been specified for the purpose of further high data rate, low delay, etc. (Non-patent Document 1). Also, LTE-A (also referred to as LTE Advanced, LTE Rel. 10, 11 or 12) has been specified for the purpose of further widening and speeding up from LTE (also referred to as LTE Rel. 8 or 9), and LTE. Successor systems (for example, FRA (Future Radio Access), 5G (5th generation mobile communication system), LTE Rel.13, Rel.14, etc.) are also being studied.

LTE Rel. In October 11, carrier aggregation (CA: Carrier Aggregation) that integrates a plurality of component carriers (CC: Component Carrier) is introduced in order to increase the bandwidth. Each CC is LTE Rel. 8 system bands are configured as one unit. In CA, a plurality of CCs of the same radio base station (eNB: eNodeB) are set as user terminals (UE: User Equipment).

Meanwhile, LTE Rel. 12, dual connectivity (DC: Dual Connectivity) in which a plurality of cell groups (CG: Cell Group) of different radio base stations is set in the user terminal is also introduced. Each cell group includes at least one cell (CC). Since a plurality of CCs of different radio base stations are integrated, DC is also called Inter-eNB CA or the like.

Also, LTE Rel. In 8-12, frequency division duplex (FDD) in which downlink (DL) transmission and uplink (UL: Uplink) transmission are performed in different frequency bands, and DL transmission and UL transmission are in the same frequency band. Time Division Duplex (TDD), which is performed by switching over time, is introduced.

LTE Rel. In 8-12, a transmission time interval (TTI) applied to DL transmission and UL transmission between the radio base station and the user terminal is set to 1 ms and controlled. The TTI in the existing system (LTE Rel. 8-12) is also called a subframe, a subframe length, or the like.

3GPP TS 36.300 Rel.8 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2”

On the other hand, Rel. In future wireless communication systems such as LTE and 5G after 13th, communication in high frequency bands such as tens of GHz, relative to IoT (Internet of Things), MTC: Machine Type Communication, M2M (Machine To Machine), etc. It is assumed that communication with a small amount of data is performed. In such a future wireless communication system, when a communication method (for example, a transmission time interval (TTI) of 1 ms) in the existing system (LTE Rel. 8-12) is applied, there is a possibility that sufficient communication service cannot be provided. .

Therefore, in a future wireless communication system, it is conceivable to perform communication using a TTI (hereinafter referred to as a shortened TTI) shorter than a 1 ms TTI (hereinafter referred to as a normal TTI). When a shortened TTI is used, there is a problem of how to configure an uplink shared channel (PUSCH: Physical Uplink Shared Channel) transmitted by the shortened TTI.

The present invention has been made in view of such points, and an object of the present invention is to provide a user terminal, a radio base station, and a radio communication method capable of performing communication using an uplink shared channel having a configuration suitable for shortened TTI. One.

One aspect of the user terminal of the present invention is a transmitter that transmits an uplink shared channel in a second TTI configured with a smaller number of symbols than a first transmission time interval (TTI), and a control that controls transmission of the uplink shared channel. And the control unit sets the second TTI to include one of two symbols to which a demodulation reference signal for the uplink shared channel of the first TTI is transmitted, and the first TTI includes the first TTI. A reference signal for demodulation of an uplink shared channel of 2TTI is transmitted.

According to the present invention, communication can be performed using an uplink shared channel having a configuration suitable for shortened TTI.

It is a figure which shows the structural example of normal TTI. 2A and 2B are diagrams illustrating a configuration example of a shortened TTI. 3A to 3C are diagrams illustrating setting examples of the shortened TTI. 4A to 4C are diagrams illustrating an example of a PUSCH configuration of normal TTI. 5A and 5B are diagrams illustrating an example of a PUSCH configuration of a shortened TTI according to the first aspect. 6A and 6B are diagrams illustrating multiplexing examples of DMRS according to the first aspect. 7A and 7B are diagrams illustrating a first mapping example of DMRS according to the first aspect. 8A to 8C are diagrams illustrating a second mapping example of DMRS according to the first aspect. 9A and 9B are explanatory diagrams of an example of the Comb according to the first aspect. 10A and 10B are diagrams illustrating another example of the PUSCH configuration of the shortened TTI according to the first aspect. 11A and 11B are diagrams illustrating an example of a PUSCH configuration of a shortened TTI according to the second aspect. It is a figure which shows the 1st example of mapping of UCI which concerns on a 2nd aspect. It is a figure which shows the 2nd example of mapping of UCI which concerns on a 2nd aspect. 14A and 14B are diagrams illustrating an example of a PUSCH configuration of a shortened TTI according to the third aspect. It is a figure which shows an example of schematic structure of the radio | wireless communications system which concerns on this Embodiment. It is a figure which shows an example of the whole structure of the wireless base station which concerns on this Embodiment. It is a figure which shows an example of a function structure of the radio base station which concerns on this Embodiment. It is a figure which shows an example of the whole structure of the user terminal which concerns on this Embodiment. It is a figure which shows an example of a function structure of the user terminal which concerns on this Embodiment. It is a figure which shows an example of the hardware constitutions of the radio base station and user terminal which concern on this Embodiment.

FIG. 1 is a diagram illustrating an example of a TTI (normal TTI) in an existing system (LTE Rel. 8-12). As shown in FIG. 1, the normal TTI has a time length of 1 ms. A normal TTI is also called a subframe and is composed of two time slots. In the existing system, the normal TTI is a transmission time unit of one channel-coded data packet, and is a processing unit such as scheduling and link adaptation.

As shown in FIG. 1, in the case of normal cyclic prefix (CP) in the downlink (DL), the normal TTI is configured to include 14 OFDM (Orthogonal Frequency Division Multiplexing) symbols (7 OFDM symbols per slot). Each OFDM symbol has a time length (symbol length) of 66.7 μs, and a normal CP of 4.76 μs is added. Since the symbol length and the subcarrier interval are inverse to each other, when the symbol length is 66.7 μs, the subcarrier interval is 15 kHz.

Also, in the case of normal cyclic prefix (CP) in the uplink (UL), the normal TTI is configured to include 14 SC-FDMA (Single Carrier Frequency Division Multiple Access) symbols (7 SC-FDMA symbols per slot). Each SC-FDMA symbol has a time length (symbol length) of 66.7 μs, and a normal CP of 4.76 μs is added. Since the symbol length and the subcarrier interval are inverse to each other, when the symbol length is 66.7 μs, the subcarrier interval is 15 kHz.

Although not shown, in the case of the extended CP, the normal TTI may be configured to include 12 OFDM symbols (or 12SC-FDMA symbols). In this case, each OFDM symbol (or each SC-FDMA symbol) has a time length of 66.7 μs, and an extended CP of 16.67 μs is added. Also, OFDM symbols may be used in the UL. Hereinafter, when the OFDM symbol and the SC-FDMA symbol are not distinguished, they are referred to as “symbols”.

On the other hand, Rel. In future wireless communication systems such as LTE and 5G after 13th, wireless interfaces suitable for high frequency bands such as tens of GHz, IoT (Internet of Things), MTC: Machine Type Communication, M2M (Machine To Machine), etc. In order to be suitable for communications with a relatively small amount of data, a wireless interface that has a small packet size but minimizes delay is desired.

When using a shortened TTI having a shorter time length than a normal TTI, a time margin for processing (for example, encoding, decoding, etc.) in a user terminal or a radio base station increases, so that processing delay can be reduced. Further, when the shortened TTI is used, the number of user terminals that can be accommodated per unit time (for example, 1 ms) can be increased. For this reason, in future wireless communication systems, it is considered to use a shortened TTI shorter than a normal TTI as a processing unit such as a transmission time unit, scheduling, and link adaptation of one channel-coded data packet.

The shortened TTI will be described with reference to FIGS. FIG. 2 is a diagram illustrating a configuration example of the shortened TTI. As shown in FIGS. 2A and 2B, the shortened TTI has a time length (TTI length) shorter than 1 ms. The shortened TTI may be, for example, one or a plurality of TTI lengths with a multiple of 1 ms, such as 0.5 ms, 0.2 ms, and 0.1 ms. Or, in the case of a normal CP, a normal TTI includes 14 symbols, so that it is one or a plurality of TTI lengths that are integer multiples of 1/14 ms, such as 7/14 ms, 4/14 ms, 3/14 ms, and 1/14 ms. May be. In addition, in the case of extended CP, since a normal TTI includes 12 symbols, it is one or a plurality of TTI lengths that are integral multiples of 1/12 ms such as 6/12 ms, 4/12 ms, 3/12 ms, and 1/12 ms. May be. In the shortened TTI, as in the conventional LTE, the normal CP or the extended CP can be configured by higher layer signaling such as broadcast information or RRC signaling. This makes it possible to introduce a shortened TTI while maintaining compatibility (synchronization) with a normal TTI of 1 ms.

FIG. 2A is a diagram illustrating a first configuration example of the shortened TTI. As shown in FIG. 2A, in the first configuration example, the shortened TTI is composed of the same number of symbols as the normal TTI (here, 14 symbols), and each symbol has a symbol length of the normal TTI (for example, 66. A symbol length shorter than 7 μs).

As shown in FIG. 2A, when the number of normal TTI symbols is maintained and the symbol length is shortened, the normal TTI physical layer signal configuration (RE arrangement or the like) can be used. In addition, when the number of symbols of normal TTI is maintained, the same amount of information (bit amount) as that of normal TTI can be included in the shortened TTI. On the other hand, since the symbol time length is different from that of the normal TTI symbol, it is difficult to frequency multiplex the shortened TTI signal and the normal TTI signal shown in FIG. 2A in the same system band (or cell, CC). It becomes.

Also, since the symbol length and the subcarrier interval are inversely related to each other, when the symbol length is shortened as shown in FIG. 2A, the subcarrier interval is usually wider than 15 kHz of TTI. When the subcarrier interval becomes wide, it is possible to effectively prevent channel-to-channel interference due to Doppler shift during movement of the user terminal and transmission quality deterioration due to phase noise of the user terminal receiver. In particular, in a high frequency band such as several tens of GHz, it is possible to effectively prevent deterioration in transmission quality by widening the subcarrier interval.

FIG. 2B is a diagram illustrating a second configuration example of the shortened TTI. As shown in FIG. 2B, in the second configuration example, the shortened TTI is configured with a smaller number of symbols than the normal TTI, and each symbol has the same symbol length (for example, 66.7 μs) as the normal TTI. . For example, in FIG. 2B, if the shortened TTI is half the time length (0.5 ms) of the normal TTI, the shortened TTI is composed of half the normal TTI symbols (here, 7 symbols).

As shown in FIG. 2B, when the number of symbols is reduced while maintaining the symbol length, the information amount (bit amount) included in the shortened TTI can be reduced as compared with the normal TTI. For this reason, the user terminal can perform reception processing (for example, demodulation, decoding, etc.) of information included in the shortened TTI in a time shorter than normal TTI, and the processing delay can be shortened. Also, the shortened TTI signal and the normal TTI signal shown in FIG. 2B can be frequency-multiplexed within the same system band (or cell, CC), and compatibility with the normal TTI can be maintained.

2A and 2B show an example of a shortened TTI that assumes a case of a normal CP (a case where a normal TTI is composed of 14 symbols), but the configuration of the shortened TTI is shown in FIGS. 2A and 2B. It is not limited to things. For example, in the case of extended CP, the shortened TTI in FIG. 2A may be configured with 12 symbols, and the shortened TTI in FIG. 2B may be configured with 6 symbols. As described above, the shortened TTI only needs to have a shorter time length than the normal TTI, and the number of symbols, the symbol length, the CP length, and the like in the shortened TTI are arbitrary.

A setting example of the shortened TTI will be described with reference to FIG. Future wireless communication systems may be configured so that both normal TTI and shortened TTI can be set so as to be compatible with existing systems.

For example, as shown in FIG. 3A, the normal TTI and the shortened TTI may be mixed in time within the same CC (frequency domain). Specifically, the shortened TTI may be set in a specific subframe of the same CC (or a specific time unit such as a specific radio frame). For example, in FIG. 3A, the shortened TTI is set in five consecutive subframes in the same CC, and the normal TTI is set in the other subframes. Note that the number and position of subframes in which the shortened TTI is set are not limited to those illustrated in FIG. 3A.

Also, as shown in FIG. 3B, carrier aggregation (CA) or dual connectivity (DC) may be performed by integrating the normal TTI CC and the shortened TTI CC. Specifically, the shortened TTI may be set in a specific CC (more specifically, in the DL and / or UL of the specific CC). For example, in FIG. 3B, a shortened TTI is set in the DL of a specific CC, and a normal TTI is set in the DL and UL of another CC. Note that the number and position of CCs for which the shortened TTI is set are not limited to those shown in FIG. 3B.

In the case of CA, the shortened TTI may be set to a specific CC (primary (P) cell or / and secondary (S) cell) of the same radio base station. On the other hand, in the case of DC, the shortened TTI may be set to a specific CC (P cell or / and S cell) in the master cell group (MCG) formed by the first radio base station, or the second radio It may be set to a specific CC (primary secondary (PS) cell or / and S cell) in the secondary cell group (SCG) formed by the base station.

Also, as shown in FIG. 3C, the shortened TTI may be set to either DL or UL. For example, in FIG. 3C, in the TDD system, the normal TTI is set in the UL and the shortened TTI is set in the DL.

Also, a specific DL or UL channel or signal may be assigned (set) to the shortened TTI. For example, the uplink control channel (PUCCH: Physical Uplink Control Channel) may be assigned to a normal TTI, and the uplink shared channel (PUSCH: Physical Uplink Shared Channel) may be assigned to a shortened TTI. For example, in this case, the user terminal performs transmission of PUCCH by normal TTI and transmission of PUSCH by shortened TTI.

In FIG. 3, the user terminal sets (or / and detects) a shortened TTI based on an implicit or explicit notification from the radio base station. In the following, (1) an implicit notification example, (2) broadcast information or RRC (Radio Resource Control) signaling, (3) MAC (Medium Access Control) signaling, (4) explicit by PHY (Physical) signaling An example of notification will be described.

(1) In the case of an implicit notification, the user terminal transmits an LBT (Listen in frequency band (for example, 5G band, unlicensed band, etc.), system bandwidth (for example, 100 MHz, etc.), LAA (License Assisted Access). Applicability of Before Talk, type of data to be transmitted (eg, control data, voice, etc.), logical channel, transport block, RLC (Radio Link Control) mode, C-RNTI (Cell-Radio Network Temporary Identifier), etc. Based on the above, a shortened TTI may be set (for example, it is determined that a cell, a channel, a signal, or the like for communication is a shortened TTI). Also, when control information (DCI) addressed to the terminal itself is detected in the PDCCH mapped to the first 1, 2, 3, or 4 symbols of the normal TTI and / or 1 ms of EPDCCH, 1 ms including the PDCCH / EPDCCH is normally used. Control information (DCI) addressed to own terminal is detected by PDCCH / EPDCCH (eg, PDCCH mapped to other than the first 1 to 4 symbols of TTI and / or EPDCCH of less than 1 ms) that has a configuration other than that determined as TTI In this case, a predetermined time interval of less than 1 ms including the PDCCH / EPDCCH may be determined as the shortened TTI. Here, the control information (DCI) addressed to the own terminal can be detected based on the CRC check result for the blind-decoded DCI.

(2) In the case of broadcast information or RRC signaling (upper layer signaling), the shortened TTI may be set based on setting information notified from the radio base station to the user terminal by broadcast information or RRC signaling. The setting information indicates, for example, which CC or / and subframe is used as a shortened TTI, which channel or / and signal is transmitted / received by the shortened TTI, or the like. The user terminal sets the shortened TTI to semi-static based on the setting information from the radio base station. Note that mode switching between the shortened TTI and the normal TTI may be performed by an RRC reconfiguration procedure, an intra-cell handover (HO) in the P cell, and a CC (S cell in the S cell. ) Removal / addition procedure.

(3) In the case of MAC signaling (L2 (Layer 2) signaling), the shortened TTI set based on the setting information notified by RRC signaling is activated or deactivated (activate or de-activate) by MAC signaling. May be. Specifically, the user terminal enables or disables the shortened TTI based on an L2 control signal (for example, a MAC control element) from the radio base station. The user terminal is set in advance with a timer indicating the activation period of the shortened TTI by higher layer signaling such as RRC. After the shortened TTI is activated by the L2 control signal, the UL / DL allocation of the shortened TTI for a predetermined period is performed. If not done, the shortened TTI may be invalidated. Such a shortened TTI invalidation timer may count in units of normal TTI (1 ms), or may count in units of shortened TTI (for example, 0.25 ms). Note that, when switching between the shortened TTI mode and the normal TTI mode in the S cell, the S cell may be de-activated once, or it may be considered that a TA (Timing Advance) timer has expired. Thereby, the communication stop period at the time of mode switching can be provided.

(4) In the case of PHY signaling (L1 (Layer 1) signaling), a shortened TTI set based on setting information notified by RRC signaling may be scheduled by PHY signaling. Specifically, the user terminal receives and detects information included in the L1 control signal (for example, downlink control channel (PDCCH: Physical Downlink Control Channel or EPDCCH: Enhanced Physical Downlink Control Channel; hereinafter referred to as PDCCH / EPDCCH)). Based on, a shortened TTI is detected.

For example, it is assumed that control information (DCI) for assigning transmission or reception in normal TTI and shortened TTI includes different information elements, and (4-1) the user terminal performs control including information elements for assigning transmission / reception in shortened TTI. When information (DCI) is detected, a predetermined time interval including the timing at which the PDCCH / EPDCCH is detected may be recognized as a shortened TTI. The user terminal can blind-decode control information (DCI) that allocates transmission or reception of both normal TTI and shortened TTI in PDCCH / EPDCCH. Alternatively, (4-2) the user terminal detects downlink control information (DCI: Downlink) transmitted by the PDCCH / EPDCCH (when the control information (DCI) including an information element to which transmission / reception with the shortened TTI is allocated is detected) A predetermined time interval including the timing at which PDSCH or PUSCH scheduled by Control Information)) is transmitted / received may be recognized as a shortened TTI. Alternatively, (4-3) the PDSCH scheduled by the PDCCH / EPDCCH (DCI transmitted by the PDCCH / EPDCCH) when the control information (DCI) including the information element to which transmission / reception with the shortened TTI is allocated is detected. Alternatively, even if a predetermined time interval including timing for transmitting or receiving retransmission control information (also referred to as HARQ-ACK (Hybrid Automatic Repeat reQuest-Acknowledgement), ACK / NACK, A / N, etc.) for PUSCH is recognized as a shortened TTI Good.

Also, the user terminal may detect the shortened TTI based on the state of the user terminal (for example, Idle state or Connected state). For example, in the idle state, the user terminal may recognize all TTIs as normal TTIs and perform blind decoding only on the PDCCH included in the first 1 to 4 symbols of the 1 ms normal TTI. Further, when the user terminal is in the connected state, the user terminal may set (or / and detect) the shortened TTI based on at least one of the above notification examples (1) to (4).

As described above, when the shortened TTI is set, there is a problem of how to configure the PUSCH transmitted by the shortened TTI. By the way, PUSCH transmitted by normal TTI (subframe) is configured as shown in FIG.

As shown in FIGS. 4A to 4C, PUSCH demodulation reference signals (DMRS: DeModulation Reference Signal, UL DMRS, etc.) that are normally transmitted in TTI are mapped to predetermined symbols in each slot constituting a subframe. . For example, when the normal CP is used (each slot is composed of 7 symbols), the DMRS is mapped to the index 3 symbol (symbol at the center of each slot) as shown in FIGS. 4A-4C. However, it is not limited to this. If extended CP is used (each slot consists of 6 symbols), the DMRS may be mapped to the index 2 symbol of each slot. Hereinafter, a predetermined symbol to which DMRS is mapped is referred to as a DMRS symbol.

Here, the DMRS sequence length is the same as the transmission bandwidth of the PUSCH demodulated using the DMRS. Further, at least 30 sequences are defined for each sequence length as DMRS sequences, and are grouped into 30 sequence groups. DMRS sequences used in the same cell belong to the same sequence group, and which sequence group (DMRS sequence index) is used in the cell may be changed between slots (group hopping). A sequence group (DMRS sequence index) may be determined based on a cell ID, may be notified to a user terminal by system information, or may be set in each PUSCH and PUCCH by user-specific RRC signaling. It may be determined based on the ID.

Also, between a plurality of synchronized cells, DMRS is mapped to the same symbol (for example, the symbol of index 3 shown in FIGS. 4A to 4C) for any user terminal in any cell. In addition, interference is randomized in a plurality of DMRSs mapped to the same symbol by a cyclic shift (CS) and an orthogonal code (OCC).

FIG. 4A shows a configuration example in the case of transmitting uplink data (also referred to as uplink user data or UL data) without transmitting uplink control information (UCI: Uplink Control Information) by PUSCH in normal TTI. In FIG. 4A, uplink data is mapped to each symbol other than two DMRS symbols.

FIG. 4B shows a configuration example in the case where both UCI and uplink data are transmitted by PUSCH in normal TTI. The UCI may include at least one of a channel quality identifier (CQI: Channel Quality Indicator), a precoding matrix identifier (PMI: Precoding Matrix Indicator), a rank identifier (RI: Rank Indicator), and the above-described HARQ-ACK.

As shown in FIG. 4B, the CQI and / or PMI (hereinafter referred to as CQI / PMI) is one PRB of a PUSCH transmission band (for example, one or more physical resource blocks (PRB)) in a normal TTI. Are mapped in the time direction to symbols excluding two DMRS symbols. HARQ-ACK is mapped in the time direction from the other PRB of the transmission band to symbols adjacent to two DMRS symbols. Also, RI is mapped in the time direction to symbols adjacent to HARQ-ACK. Uplink data, CQI / PMI, and RI are encoded and rate matched, multiplexed, and punctured based on HARQ-ACK.

FIG. 4C shows a configuration example in the case where UCI is transmitted by PUSCH in normal TTI. In FIG. 4C, as in FIG. 4B, CQI / PMI, HARQ-ACK, and RI are mapped to symbols in normal TTI.

4A-4C, the mapping image before applying DFT (Discrete Fourier Transform) is exemplified. The symbols that are actually transmitted may be arranged interleaved in the frequency direction. The mapping images shown below are all before DFT application. Also, DFT is not applied to DMRS.

The PUSCH in normal TTI is transmitted using the configuration shown in FIGS. 4A-4C. However, it is assumed that the PUSCH configuration in the normal TTI as described above cannot be directly applied to a shortened TTI (see FIG. 2B) configured with a smaller number of symbols than the normal TTI. On the other hand, when configuring PUSCH of shortened TTI without considering PUSCH configuration (particularly, DMRS symbols of each slot) in normal TTI, interference to user terminals (legacy UEs) that transmit PUSCH using normal TTI May increase.

Accordingly, the present inventors have conceived of including at least one DMRS symbol per shortened TTI configured with a smaller number of symbols than the normal TTI while maintaining the DMRS symbol of the normal TTI, and reached the present invention. . Specifically, in the present invention, a shortened TTI is set so as to include one of 2DMRS symbols in a normal TTI, and a PUSCH DMRS of the shortened TTI is transmitted / received in the one symbol.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the present embodiment, the shortened TTI (second TTI) is configured with a smaller number of symbols than the normal TTI (first TTI), and each symbol has the same symbol length as the normal TTI (FIG. 2B). reference). Note that the number of shortened TTIs included in the normal TTI is, for example, 2, 4, but is not limited thereto.

The shortened TTI is also called partial TTI (short TTI), short TTI, sTTI, shortened subframe, short subframe, etc., and the normal TTI is usually TTI, long TTI, lTTI, normal TTI, It is also called a normal subframe, a long subframe, a normal subframe, or simply a subframe. Moreover, although the case where normal CP is applied to each symbol below is illustrated, it is not limited to this. The present embodiment can be applied as appropriate when an extended CP is applied to each symbol.

(First aspect)
In the first mode, a configuration example of PUSCH in the case where uplink data is transmitted without transmitting UCI using PUSCH allocated by shortened TTI will be described.

<When maintaining DMRS symbols>
FIG. 5 is a diagram illustrating an example of a PUSCH configuration in the shortened TTI (sTTI) according to the first aspect. FIG. 5A illustrates a case where two sTTIs are included per normal TTI (subframe), and FIG. 5B illustrates a case where four sTTIs are included per subframe. As shown in FIGS. 5A and 5B, in a subframe including a plurality of sTTIs, a DMRS symbol is provided in the same symbol (center symbol of each slot) of normal TTIs.

In FIG. 5A, each sTTI is composed of 7 symbols including DMRS symbols. The user terminal maps the sTTI-1 DMRS to the DMRS symbol in the first slot (hereinafter referred to as the first DMRS symbol), and maps the sTTI-2 DMRS to the DMRS symbol in the second slot (hereinafter referred to as the second DMRS symbol). To do.

On the other hand, in FIG. 5B, each sTTI is composed of 4 symbols including DMRS symbols shared among a plurality of sTTIs. The first DMRS symbol is included in both sTTI-1 and STTI-2, and is shared by sTTI-1 and sTTI-2. The second DMRS symbol is included in both sTTI-3 and STTI-4, and is shared by sTTI-3 and STTI-4.

5A and 5B, in different sTTIs, different user terminals may transmit PUSCH, or the same user terminal may transmit PUSCH. Although not shown, the configuration examples shown in FIGS. 5A and 5B may be combined. For example, one sTTI may be set in the first slot of the subframe as shown in FIG. 5A, and two sTTIs may be set in the second slot as shown in FIG. 5B. It may be set.

As illustrated in FIG. 5A, when a single DMRS symbol is used in a single sTTI, the user terminal, like a normal TTI DMRS, includes a CS / OCC indication field (included in the DCI to which the PUSCH of the sTTI is allocated). A DMRS can be generated using a cyclic shift index (CS index) and OCC indicated by the CS / OCC indicator field.

On the other hand, as shown in FIG. 5B, when a single DMRS symbol is shared by a plurality of sTTIs, the DMRSs of the plurality of sTTIs are multiplexed into a single DMRS symbol. For example, as shown in FIG. 5B, when a single DMRS symbol is shared by a plurality of sTTIs, the DMRSs of the plurality of sTTIs are multiplexed by a cyclic shift and / or a comb-shaped subcarrier arrangement (Comb). May be.

FIG. 6 is a diagram showing a multiplexing example of a plurality of sTTI DMRS sharing the same DMRS symbol. Note that FIG. 6 illustrates an example of multiplexing DMRS when sTTI-1 and sTTI-2 in FIG. 5B share the first DMRS symbol, but the second DMRS symbol is used for sTTI-3 and sTTI-4. The same applies to sharing.

FIG. 6A shows an example of multiplexing using a cyclic shift. Each sTTI DMRS is generated using a different CS index and mapped to the same DMRS symbol. For example, in FIG. 6A, the sTTI-1 DMRS is generated using the CS index #x, while the sTTI-2 DMRS is generated using the CS index #y. Note that the CS index of each sTTI may be indicated by a predetermined field in the DCI (for example, a CS / OCC instruction field, a cyclic shift field, etc.).

FIG. 6B shows an example of multiplexing using Comb. As shown in FIG. 6B, the subcarriers of Comb # 0 and # 1 are alternately arranged. A different comb (subcarrier) is assigned to each sTTI DMRS. For example, in FIG. 6B, Comb # 0 is assigned to the sTTI-1 DMRS, while Comb # 1 is assigned to the sTTI-2 DMRS. The Comb of each sTTI may be specified by a predetermined field (for example, CS / OCC field) in the DCI (for example, Comb # 0 if the predetermined field value = 0) or determined in advance depending on which sTTI is used. (For example, Comb # 0 for sTTI1).

6A and 6B, when the same user terminal transmits a PUSCH with a plurality of sTTIs sharing a single DMRS symbol, the user terminal generates only one DMRS of the plurality of sTTIs. You may send it. In this case, for example, in FIG. 6A, DMRS is generated using either CS index #x or #y, and in FIG. 6B, DMRS is mapped to either Comb # 0 or # 1.

Moreover, DMRS of each sTTI may be multiplexed using both the cyclic shift shown in FIG. 6A and the Comb shown in FIG. 6B. In this case, three or more DMRSs can be multiplexed by multiplexing a plurality of DMRSs by cyclic shift in the same comb.

Referring to FIGS. 7 and 8, an example of mapping of DMRSs of a plurality of sTTIs sharing the same DMRS symbol will be described. FIG. 7 is a diagram illustrating a case where the same user terminal transmits PUSCH among a plurality of sTTIs sharing the same DMRS symbol. In FIG. 7, since a plurality of sTTI PUSCHs are allocated to the same user terminal, the user terminal may transmit only one DMRS of the plurality of sTTIs.

In FIG. 7A, PUSCH can be assigned to different PRBs among a plurality of sTTIs sharing the same DMRS symbol. In this case, the DMRS may be mapped to a PRB including at least a PRB (assigned PRB) assigned to the PUSCH by the plurality of sTTIs. The user terminal determines a PRB (mapping PRB) to which DMRS is mapped (transmitted) based on the assigned PRBs in a plurality of sTTIs sharing the same DMRS symbol.

For example, in FIG. 7A, the user terminal maps and transmits DMRS of either sTTI-1 or sTTI-2 to consecutive PRBs including the assigned PRBs of sTTI-1 and sTTI-2 in the first DMRS symbol. To do. Further, the user terminal maps and transmits DMRS of either sTTI-3 or sTTI-4 to consecutive PRBs including the assigned PRBs of sTTI-3 and sTTI-4 in the second DMRS symbol.

In addition, when there is no PUSCH allocation to the user terminal in sTTI-2, the user terminal may map and transmit the DMRS of sTTI-1 to the allocated PRB of sTTI-1 in the first DMRS symbol. Similarly, when there is no PUSCH allocation to the user terminal in sTTI-4, the user terminal may map and transmit the DMRS of sTTI-3 to the allocated PRB of sTTI-3 in the second DMRS symbol. Similarly, when there is no PUSCH allocation to the user terminal in sTTI-1, the user terminal may map and transmit the DMRS of sTTI-2 to the allocated PRB of sTTI-2 in the first DMRS symbol. Similarly, when there is no PUSCH allocation to the user terminal in sTTI-3, the user terminal may map and transmit the DMRS of sTTI-4 to the allocated PRB of sTTI-4 in the second DMRS symbol.

In the case shown in FIG. 7A, the mapping PRB in the DMRS symbol is determined based on the allocation PRB of the plurality of sTTIs sharing the same DMRS symbol, so that the PUSCH can be flexibly allocated in the plurality of sTTIs, and Channel estimation in all PRBs assigned with multiple sTTIs can be performed. Also, DMRS can be mapped in consideration of the plurality of sTTIs in the DMRS symbol.

In FIG. 7B, PUSCH is assigned to the same PRB among a plurality of sTTIs sharing the same DMRS symbol (PUSCH cannot be assigned to different PRBs). In this case, the DMRS is mapped to the same PRB as the assigned PRB of any of the plurality of sTTIs. The user terminal determines a mapping PRB in the DMRS symbol based on the assigned PRB in any of a plurality of sTTIs sharing the same DMRS symbol (for example, the first sTTI).

For example, in FIG. 7B, in the first DMRS symbol, the user terminal maps and transmits only the sTTI-1 DMRS to the sTTI-1 assigned PRB. In this case, it is assumed that a user terminal scheduled for PUSCH in sTTI-1 is not assigned a different PRB in sTTI-2. Similarly, in the second DMRS symbol, the user terminal maps and transmits only the sTTI-3 DMRS to the sTTI-3 allocated PRB. In this case, it is assumed that the user terminal scheduled for PUSCH in sTTI-4 is not assigned a different PRB in sTTI-4.

In the case shown in FIG. 7B, the mapping PRB and the DMRS sequence in the DMRS symbol are determined only by the first sTTI among the plurality of sTTIs sharing the same DMRS symbol, so that the time-sequential sTTI allocation information is decoded. Since channel estimation can be started without waiting, the effect of reducing processing delay can be improved.

FIG. 8 is a diagram illustrating a case where different user terminals transmit PUSCH among a plurality of sTTIs sharing the same DMRS symbol. In FIG. 8, since PUSCH is allocated to different user terminals among the plurality of sTTIs, different CS indexes and / or different Combs are applied to DMRSs of the plurality of sTTIs.

In FIG. 8A, PUSCHs are assigned to different PRBs among a plurality of sTTIs sharing the same DMRS symbol. In this case, the plurality of sTTI DMRSs may be multiplexed using Comb. Specifically, the DMRSs of the plurality of sTTIs are mapped to different Combs in each sTTI allocation PRB.

For example, in FIG. 8A, it is assumed that Comb # 0 is assigned to the DMRS of sTTI-1 and Comb # 1 is assigned to the DMRS of sTTI-2. In this case, the user terminal maps the DMRS of sTTI-1 to Comb # 0 in the assigned PRB of sTTI-1. On the other hand, the user terminal maps the DMRS of sTTI-2 to Comb # 1 in the assigned PRB of sTTI-2.

Thereby, as shown in FIG. 8B, in the PRB to which the PUSCH is assigned only in sTTI-1, the DMRS is mapped only to the subcarrier of Comb # 0. On the other hand, in PRB to which PUSCH is assigned only in sTTI-2, DMRS is mapped only to the subcarrier of Comb # 1. Also, in the PRB to which PUSCH is allocated in both sTTI-1 and sTTI-2, DMRS is mapped to the subcarriers of Comb # 0 and # 1.

As shown in FIGS. 8A and 8B, when a plurality of sTTI DMRS sharing the same DMRS symbol are multiplexed by Comb, different PRBs can be allocated to PUSCH among the plurality of sTTIs. As a result, flexible scheduling can be performed.

In FIG. 8C, PUSCH is assigned to the same PRB among a plurality of sTTIs sharing the same DMRS symbol. In this case, the plurality of sTTI DMRSs may be multiplexed using a cyclic shift. Specifically, the plurality of sTTI DMRSs are mapped to the same PRB using different CS indexes. The user terminal determines a mapping PRB in the DMRS symbol based on the assigned PRB in any one of the plurality of sTTIs (for example, the first sTTI).

For example, in FIG. 8C, the user terminal generates a DMRS of sTTI-1 and a DMRS of sTTI-2 using different CS indexes, and maps them to the assigned PRB of sTTI-1 in the first DMRS symbol. In this case, it is assumed that a user terminal scheduled for PUSCH in sTTI-1 is not assigned a different PRB in sTTI-2. The same applies to sTTI-3 and sTTI-4.

As shown in FIG. 8C, when it is assumed that a PUSCH is allocated to the same PRB among a plurality of sTTIs sharing the same DMRS symbol, a DMRS of a plurality of sTTIs can be multiplexed by a cyclic shift, and a Comb is applied to the DMRS. It is possible to improve compatibility with existing systems that do not. Also, since the DMRS mapping PRB can be determined by only the first sTTI among the plurality of sTTIs, the effect of reducing the processing delay can be improved.

8A and 8B, when a plurality of sTTI DMRSs sharing the same DMRS symbol are multiplexed by Comb, Comb may be explicitly assigned to each sTTI DMRS, or implicitly assigned. May be.

Specifically, the Comb index may be indicated by the value of a predetermined field (eg, CS / OCC indication field, cyclic shift field, etc.) included in DCI (eg, UL grant to which PUSCH is allocated). For example, if the CS / OCC indication field value is 0, it may indicate Comb index # 0, and if the CS / OCC indication field value is 1, it may indicate Comb index # 1.

Alternatively, the user terminal may determine the Comb index based on the position, index, and the like of sTTI that transmits PUSCH (PUSCH is scheduled). In this case, which Comb is allocated to each sTTI sharing the same DMRS symbol may be determined in advance or may be notified by higher layer signaling. For example, in FIG. 8A, the user terminal determines Comb index # 0 for the DMRS of sTTI-1 (or sTTI-3), and the Comb index for the DMRS of sTTI-2 (or sTTI-4) # 1 may be determined.

In addition, when Comb is applied to DMRS of each sTTI, the user terminal may control PUSCH transmission power based on the number of Combs. FIG. 9 is a diagram illustrating the relationship between transmission power and PSD (Power Spectrum Density). As shown in FIG. 9A, when the transmission power of the DMRS and PUSCH to which the Comb is applied is the same, the PSD of the DMRS becomes the number of combs of the PSD of the PUSCH (here, 2) times.

For this reason, the user terminal may multiply the transmission power of the DMRS to which the Comb is applied by 1 / Comb number (in this case, 1/2) times. As a result, as shown in FIG. 9B, the PSD of the DMRS becomes low, and the PSD of the DMRS and the PSD of the PUSCH become equivalent. As a result, it is possible to suppress interference from other cells due to DMRS and to easily estimate the reception SINR of uplink data.

Also, when PUSCH is assigned to the same PRB among a plurality of sTTIs sharing the same DMRS symbol, in FIG. 8C, the DMRSs of the plurality of sTTIs are multiplexed by cyclic shift. Absent. The plurality of sTTI DMRSs may be multiplexed by Comb.

As described above, when mapping the DMRS of the sTTI configured with the number of symbols smaller than the normal TTI to the DMRS symbol of each slot of the normal TTI, the interference with the legacy UE that transmits the PUSCH with the normal TTI is not increased. In addition, PUSCH can be transmitted by sTTI, and processing delay can be reduced.

<Increasing DMRS symbols>
A case where an additional DMRS symbol (hereinafter referred to as an additional DMRS symbol) is provided in each sTTI in addition to the first and second DMRS symbols will be described with reference to FIG. Note that FIG. 10 will be described with a focus on differences from FIG.

FIG. 10 is a diagram illustrating another example of the PUSCH configuration in the sTTI according to the first aspect. FIG. 10A illustrates a case where two sTTIs are included per subframe, and FIG. 10B illustrates a case where four sTTIs are included per subframe. As shown in FIGS. 10A and 10B, in a subframe including a plurality of sTTIs, an additional DMRS symbol may be provided for each sTTI in addition to the first and second DMRS symbols.

For example, in FIG. 10A, an additional DMRS symbol is provided in the first symbol (index 0) in sTTI-1, and an additional DMRS symbol is provided in the last symbol (index 6) in sTTI-2. Similarly, in FIG. 10B, in sTTI-1, an additional DMRS symbol is provided in the first symbol (index 0), and in sTTI-2, an additional DMRS symbol is provided in the last symbol (index 6). The same applies to sTTI-3 and sTTI-4. Note that the position of the additional DMRS symbol is not limited to that shown in FIGS. 10A and 10B.

10A and 10B, the DMRS of the first and second DMRS symbols can be generated using at least one of the CS index, OCC, and Comb as described with reference to FIGS. 5-8. Thereby, orthogonality and randomization with the legacy UE that transmits the PUSCH in the normal TTI can be ensured.

Meanwhile, the DMRS of the additional DMRS symbol may be generated using a DMRS sequence and / or CS index of a group (DMRS sequence index) different from the first and second DMRS symbols. At this time, for example, based on the cell ID or the virtual cell ID, the group (DMRS sequence index) for generating the DMRS sequence may be changed between the first and second DMRS symbols and the additional DMRS symbol. Thereby, since the hopping rule of a group (DMRS sequence index) can be made different between user terminals connected to different cells, it becomes possible to increase the randomization of inter-cell interference.

10A and 10B, since two DMRS symbols are included per sTTI, as in the case of normal TTI, the PUSCH channel estimation accuracy transmitted by sTTI may be set to the same level as PUSCH transmitted by normal TTI. it can. For this reason, the channel estimation accuracy of PUSCH transmitted by sTTI can be improved compared with the configuration shown in FIGS. 5A and 5B.

10A and 10B are merely examples, and the number of DMRS symbols in the sTTI is not limited to this. For example, in FIGS. 10A and 10B, by providing two or more additional DMRS symbols, three or more DMRS symbols may be provided per sTTI. The channel estimation accuracy can be further improved by increasing the number of DMRS symbols per sTTI.

Also, it is assumed that a sounding reference signal (SRS) is arranged in the last symbol of the normal TTI instead of uplink data. Therefore, the additional DMRS symbol may be set to the last symbol of the last sTTI (for example, sTTI-2 in FIG. 10A, sTTI-4 in FIG. 10B) in the subframe. Accordingly, when a legacy UE that transmits PUSCH using normal TTI uses a format (Shortened format) in which uplink data is not allocated to the final symbol, interference from the DMRS of sTTI (additional DMRS) in the final symbol can be avoided.

As described above, when an additional DMRS symbol is provided, channel estimation accuracy of PUSCH transmitted by sTTI can be improved while preventing interference with a legacy UE that transmits PUSCH by normal TTI.

(Second aspect)
In the second mode, a configuration example of PUSCH in the case where both UCI and uplink data are transmitted using PUSCH assigned by sTTI will be described. Since the DMRS transmission method in each sTTI in the second mode is the same as in the first mode, description thereof is omitted. In the second aspect, mapping of UCI and uplink data to the resource element (RE) in the sTTI configured as described in the first aspect will be described in detail.

In the following, the case of maintaining the first and second DMRS symbols similar to the normal TTI (FIG. 5) will be described, but the present invention is not limited to this. The UCI and uplink data mapping method in the second mode can be applied as appropriate to the case where an additional DMRS symbol is provided in each sTTI in addition to the first and second DMRS symbols (FIG. 10).

FIG. 11 is a diagram illustrating an example of a PUSCH configuration in sTTI according to the second aspect. FIG. 11A illustrates a case where two sTTIs are included per subframe, and FIG. 11B illustrates a case where four sTTIs are included per subframe. Note that in FIGS. 11A and 11B, a plurality of shortened TTIs have different UCIs regardless of whether a PUSCH is assigned to the same user terminal in a plurality of sTTIs or a PUSCH is assigned to different user terminals. And uplink data are mapped.

As shown in FIGS. 11A and 11B, in each sTTI, the UCI may be mapped using the same rule as the UCI mapped in the normal TTI. 12 and 13 are diagrams showing mapping rules in the sTTI configuration shown in FIGS. 11A and 11B, respectively. 12 and 13, the numbers assigned to resources indicate the mapping order of CQI / PMI, RI, and HARQ-ACK.

As shown in FIG. 12, in each sTTI, the CQI / PMI is mapped in the time direction to a symbol excluding the DMRS symbol from one PRB of the PUSCH transmission band. Further, HARQ-ACK is mapped in the time direction from the other PRB of the transmission band to two symbols adjacent to the DMRS symbol. Further, RI is mapped in the time direction to two symbols outside the two symbols to which HARQ-ACK is mapped.

In FIG. 12, the uplink data is encoded and rate-matched, multiplexed with CQI / PMI and RI, and punctured based on HARQ-ACK. As shown in FIG. 12, even when the same mapping rule of normal TTI is applied, UCI and uplink data of each sTTI are mapped and mapped only to symbols excluding DMRS symbols in each sTTI. The number of REs is usually reduced compared to TTI.

Similarly, in the case shown in FIG. 13, the UCI and uplink data of each sTTI are mapped to only symbols excluding DMRS symbols in each sTTI by applying the normal TTI mapping rule, and the number of REs to be mapped Usually decreases compared to TTI. In FIG. 13, HARQ-ACK and RI are each mapped to a single symbol in each sTTI. Therefore, the mapping in the time direction of HARQ-ACK and RI in FIG. 13 is synonymous with the mapping in the frequency direction.

(Third aspect)
In the third mode, a configuration example of PUSCH in the case of transmitting UCI without transmitting uplink data using PUSCH allocated by sTTI will be described. The PUSCH configuration according to the third aspect is the same as the second aspect except that there is no uplink data mapping.

FIG. 14 is a diagram illustrating an example of a PUSCH configuration in the shortened TTI according to the third aspect. The PUSCH configuration shown in FIGS. 14A and 14B is the same as the PUSCH configuration described in the second mode (FIGS. 11A and 11B) except that there is no uplink data mapping. Since the mapping method of UCI of each sTTI in FIGS. 14A and 14B is the same as that in the second mode, description thereof is omitted.

In addition, although FIG. 14 demonstrates the case where the 1st and 2nd DMRS symbol similar to normal TTI is maintained (FIG. 5), it is not restricted to this. The UCI mapping technique in the third aspect is also applicable to cases where additional DMRS symbols are provided in each sTTI in addition to the first and second DMRS symbols (FIG. 10).

(Other)
As described in the second and third aspects, when UCI is transmitted using PUSCH of sTTI (UCI on PUSCH), even if payload restriction is performed according to a rule different from UCI transmitted using PUSCH of normal TTI. Good.

For example, in the second and third aspects, when the payload of the HARQ-ACK exceeds a predetermined threshold, or the ratio of the HARQ-ACK payload to the number of PUSCH REs (that is, the coding rate) exceeds the predetermined threshold. If so, spatial bundling may be applied. The predetermined threshold may be notified to the user terminal by higher layer signaling.

Further, in the second and third aspects, when the CQI / PMI payload exceeds a predetermined threshold, or the ratio of the CQI / PMI payload to the number of PUSCH REs (that is, the coding rate) has a predetermined threshold. If so, the lower priority CQI / PMI may be dropped (transmission may be aborted). Note that the priority of CQI / PMI may be the same as the priority in the existing system.

For example, in the second and third aspects, when the RI payload exceeds a predetermined threshold, or when the ratio of the RI payload to the PUSCH RE number (that is, the coding rate) exceeds a predetermined threshold, a plurality of The RIs of the cells may be combined. It should be noted that which cell's RI is to be combined may be notified to the user terminal by higher layer signaling. As a method for combining RIs of a plurality of cells, (1) using an average of RIs of a plurality of cells, (2) using a maximum value of RIs of a plurality of cells, and (3) a minimum of RIs of a plurality of cells. It is conceivable to use a value.

Alternatively, the data included in the PUSCH transmitted by sTTI, CQI / PMI, RI, and HARQ-ACK may be regarded as a single codeword, and may be jointly encoded. As a result, it is possible to omit CRC bits individually added to data and UCI, thereby reducing overhead. If the data (transport block) is large and is divided into a plurality of code blocks and encoded respectively, UCI may be jointly encoded to the code block of the first, last, or specific order. Good. At this time, the concatenated bit string of data and UCI may be configured in the order of data, HARQ-ACK, RI, and CQI / PMI. When the bit string size is excessive with respect to the amount of radio resources, all or part of CQI / PMI is dropped (dropped), but the codeword bit string data, HARQ-ACK, and RI positions are affected before and after dropping. Therefore, the encoding process can be simplified. Further, the same order as that of data can be applied as the order of mapping the coded bits to the radio resources when joint coding is performed.

(Wireless communication system)
Hereinafter, a configuration of a wireless communication system according to an embodiment of the present invention will be described. In this radio communication system, the radio communication method according to each of the above aspects is applied. In addition, the radio | wireless communication method which concerns on each said aspect may be applied independently, respectively, and may be applied in combination.

FIG. 15 is a diagram illustrating an example of a schematic configuration of the wireless communication system according to the present embodiment. In the radio communication system 1, carrier aggregation (CA) and / or dual connectivity (DC) in which a plurality of basic frequency blocks (component carriers) each having a system bandwidth (for example, 20 MHz) of the LTE system as one unit are applied. can do. The wireless communication system 1 may be referred to as SUPER 3G, LTE-A (LTE-Advanced), IMT-Advanced, 4G, 5G, FRA (Future Radio Access), or the like.

A radio communication system 1 shown in FIG. 15 includes a radio base station 11 that forms a macro cell C1, and radio base stations 12a to 12c that are arranged in the macro cell C1 and form a small cell C2 that is narrower than the macro cell C1. . Moreover, the user terminal 20 is arrange | positioned at the macrocell C1 and each small cell C2.

The user terminal 20 can be connected to both the radio base station 11 and the radio base station 12. It is assumed that the user terminal 20 uses the macro cell C1 and the small cell C2 that use different frequencies simultaneously by CA or DC. In addition, the user terminal 20 can apply CA or DC using a plurality of cells (CC) (for example, six or more CCs).

Communication between the user terminal 20 and the radio base station 11 can be performed using a carrier having a relatively low frequency band (for example, 2 GHz) and a narrow bandwidth (referred to as an existing carrier or a legacy carrier). On the other hand, a carrier having a relatively high frequency band (for example, 3.5 GHz, 5 GHz, etc.) and a wide bandwidth may be used between the user terminal 20 and the radio base station 12, or The same carrier may be used. The configuration of the frequency band used by each radio base station is not limited to this.

Between the wireless base station 11 and the wireless base station 12 (or between the two wireless base stations 12), a wired connection (for example, an optical fiber compliant with CPRI (Common Public Radio Interface), an X2 interface, etc.) or a wireless connection It can be set as the structure to do.

The radio base station 11 and each radio base station 12 are connected to the higher station apparatus 30 and connected to the core network 40 via the higher station apparatus 30. The upper station device 30 includes, for example, an access gateway device, a radio network controller (RNC), a mobility management entity (MME), and the like, but is not limited thereto. Each radio base station 12 may be connected to the higher station apparatus 30 via the radio base station 11.

The radio base station 11 is a radio base station having a relatively wide coverage, and may be called a macro base station, an aggregation node, an eNB (eNodeB), a transmission / reception point, or the like. The radio base station 12 is a radio base station having local coverage, and includes a small base station, a micro base station, a pico base station, a femto base station, a HeNB (Home eNodeB), an RRH (Remote Radio Head), and transmission / reception. It may be called a point. Hereinafter, when the radio base stations 11 and 12 are not distinguished, they are collectively referred to as a radio base station 10.

Each user terminal 20 is a terminal compatible with various communication methods such as LTE and LTE-A, and may include not only a mobile communication terminal but also a fixed communication terminal.

In the radio communication system 1, OFDMA (orthogonal frequency division multiple access) is applied to the downlink and SC-FDMA (single carrier-frequency division multiple access) is applied to the uplink as the radio access scheme. OFDMA is a multi-carrier transmission scheme that performs communication by dividing a frequency band into a plurality of narrow frequency bands (subcarriers) and mapping data to each subcarrier. SC-FDMA is a single-carrier transmission scheme that reduces interference between terminals by dividing the system bandwidth into bands consisting of one or continuous resource blocks for each terminal and using a plurality of terminals with mutually different bands. is there. The uplink and downlink radio access schemes are not limited to these combinations, and OFDMA may be used in the uplink.

In the wireless communication system 1, downlink channels include a downlink shared channel (PDSCH) shared by each user terminal 20, a broadcast channel (PBCH: Physical Broadcast Channel), a downlink L1 / L2 control channel, and the like. Used. User data, higher layer control information, SIB (System Information Block), etc. are transmitted by PDSCH. Also, MIB (Master Information Block) is transmitted by PBCH.

Downlink L1 / L2 control channels include downlink control channels (PDCCH (Physical Downlink Control Channel), EPDCCH (Enhanced Physical Downlink Control Channel)), PCFICH (Physical Control Format Indicator Channel), PHICH (Physical Hybrid-ARQ Indicator Channel), etc. Including. Downlink control information (DCI: Downlink Control Information) including scheduling information of PDSCH and PUSCH is transmitted by PDCCH. The number of OFDM symbols used for PDCCH is transmitted by PCFICH. The HAICH transmission confirmation information (ACK / NACK) for PUSCH is transmitted by PHICH. EPDCCH is frequency-division multiplexed with PDSCH (downlink shared data channel), and is used for transmission of DCI and the like in the same manner as PDCCH.

In the wireless communication system 1, as an uplink channel, an uplink shared channel (PUSCH) shared by each user terminal 20, an uplink control channel (PUCCH: Physical Uplink Control Channel), a random access channel (PRACH: Physical Random Access Channel) is used. User data and higher layer control information are transmitted by the PUSCH. Uplink control information (UCI) including at least one of delivery confirmation information (ACK / NACK) and radio quality information (CQI) is transmitted by PUSCH or PUCCH. A random access preamble for establishing connection with a cell is transmitted by the PRACH.

<Wireless base station>
FIG. 16 is a diagram illustrating an example of the overall configuration of the radio base station according to the present embodiment. The radio base station 10 includes a plurality of transmission / reception antennas 101, an amplifier unit 102, a transmission / reception unit 103, a baseband signal processing unit 104, a call processing unit 105, and a transmission path interface 106. Note that each of the transmission / reception antenna 101, the amplifier unit 102, and the transmission / reception unit 103 may include one or more.

User data transmitted from the radio base station 10 to the user terminal 20 via the downlink is input from the higher station apparatus 30 to the baseband signal processing unit 104 via the transmission path interface 106.

In the baseband signal processing unit 104, with respect to user data, PDCP (Packet Data Convergence Protocol) layer processing, user data division / combination, RLC (Radio Link Control) retransmission control and other RLC layer transmission processing, MAC (Medium Access) Control) Retransmission control (for example, HARQ (Hybrid Automatic Repeat reQuest) transmission processing), scheduling, transmission format selection, channel coding, inverse fast Fourier transform (IFFT) processing, precoding processing, and other transmission processing Is transferred to the transmission / reception unit 103. The downlink control signal is also subjected to transmission processing such as channel coding and inverse fast Fourier transform, and is transferred to the transmission / reception unit 103.

The transmission / reception unit 103 converts the baseband signal output by precoding for each antenna from the baseband signal processing unit 104 to a radio frequency band and transmits the converted signal. The radio frequency signal frequency-converted by the transmission / reception unit 103 is amplified by the amplifier unit 102 and transmitted from the transmission / reception antenna 101.

The transmitter / receiver, the transmission / reception circuit, or the transmission / reception device can be configured based on common recognition in the technical field according to the present invention. In addition, the transmission / reception part 103 may be comprised as an integral transmission / reception part, and may be comprised from a transmission part and a receiving part.

On the other hand, for the upstream signal, the radio frequency signal received by the transmission / reception antenna 101 is amplified by the amplifier unit 102. The transmission / reception unit 103 receives the uplink signal amplified by the amplifier unit 102. The transmission / reception unit 103 converts the frequency of the received signal into a baseband signal and outputs it to the baseband signal processing unit 104.

Also, the transmission / reception unit 103 receives the PUSCH in a shortened TTI (second TTI) configured with a smaller number of symbols than the normal TTI (first TTI). The PUSCH may include uplink data (first mode), both uplink data and UCI (second mode), or UCI (first mode). 3 embodiment).

In addition, when the shortened TTI is set so as to include one of the two symbols from which the DMRS (demodulation reference signal) of the PUSCH of the normal TTI is received, the transmission / reception section 103 uses the one symbol for the PUSCH of the shortened TTI. Receive DMRS. Further, when an additional DMRS symbol is set in the shortened TTI, the transmission / reception unit 103 may receive the DMRS of the shortened TTI using the additional DMRS symbol.

The baseband signal processing unit 104 performs fast Fourier transform (FFT) processing, inverse discrete Fourier transform (IDFT: Inverse Discrete Fourier Transform) processing, and error correction on user data included in the input upstream signal. Decoding, MAC retransmission control reception processing, RLC layer and PDCP layer reception processing are performed and transferred to the upper station apparatus 30 via the transmission path interface 106. The call processing unit 105 performs call processing such as communication channel setting and release, state management of the radio base station 10, and radio resource management.

The transmission path interface 106 transmits and receives signals to and from the higher station apparatus 30 via a predetermined interface. The transmission path interface 106 transmits and receives (backhaul signaling) signals to and from the adjacent radio base station 10 via an interface between base stations (for example, an optical fiber compliant with CPRI (Common Public Radio Interface), X2 interface). Also good.

FIG. 17 is a diagram illustrating an example of a functional configuration of the radio base station according to the present embodiment. Note that FIG. 17 mainly shows functional blocks of characteristic portions in the present embodiment, and the radio base station 10 also has other functional blocks necessary for radio communication. As illustrated in FIG. 17, the baseband signal processing unit 104 includes a control unit 301, a transmission signal generation unit 302, a mapping unit 303, and a reception signal processing unit 304.

The control unit 301 controls the entire radio base station 10. The control unit 301 controls, for example, downlink signal generation by the transmission signal generation unit 302, signal mapping by the mapping unit 303, and signal reception processing by the reception signal processing unit 304.

Specifically, the control unit 301 performs downlink (DL) signal transmission control (for example, modulation scheme, coding rate, resource allocation (scheduling)) based on channel state information (CSI) reported from the user terminal 20. Control).

Further, the control unit 301 controls a transmission time interval (TTI) used for receiving a downlink signal and / or transmitting an uplink signal. The control unit 301 sets a normal TTI of 1 ms or / and a shortened TTI shorter than the normal TTI. The configuration example and setting example of the shortened TTI are as described with reference to FIGS. The control unit 301 provides the user terminal 20 with an explicit notification by at least one of (1) implicit notification, or (2) RRC signaling, (3) MAC signaling, and (4) PHY signaling. The setting of the shortened TTI may be instructed.

Specifically, the control unit 301 sets each shortened TTI (second TTI) so as to include one of two symbols (DMRS symbols) in which the DMRS of the PUSCH of the normal TTI (first TTI) is transmitted (FIG. 5). 10, 11 and 14). The control unit 301 controls the received signal processing unit 304 to demodulate the PUSCH in the shortened TTI based on the DMRS received by the 1 DMRS symbol (or the 1 DMRS symbol and the additional DMRS symbol).

The control unit 301 can be configured by a controller, a control circuit, or a control device described based on common recognition in the technical field according to the present invention.

The transmission signal generation unit 302 generates a downlink signal (including a downlink data signal and a downlink control signal) based on an instruction from the control unit 301 and outputs it to the mapping unit 303. Specifically, the transmission signal generation unit 302 generates a downlink data signal (PDSCH) including notification information (control information) by the above-described higher layer signaling and user data, and outputs it to the mapping unit 303. Also, the transmission signal generation unit 302 generates a downlink control signal (PDCCH / EPDCCH) including the above-described DCI, and outputs it to the mapping unit 303. Also, the transmission signal generation unit 302 generates downlink reference signals such as CRS and CSI-RS, and outputs them to the mapping unit 303.

The transmission signal generation unit 302 can be a signal generator, a signal generation circuit, or a signal generation device described based on common recognition in the technical field according to the present invention.

The mapping unit 303 maps the downlink signal generated by the transmission signal generation unit 302 to a predetermined radio resource based on an instruction from the control unit 301, and outputs it to the transmission / reception unit 103. The mapping unit 303 can be a mapper, a mapping circuit, or a mapping device described based on common recognition in the technical field according to the present invention.

The reception signal processing unit 304 performs reception processing (for example, demapping, demodulation, decoding, etc.) on the uplink signal transmitted from the user terminal 20. Specifically, received signal processing section 304 demodulates the PUSCH in the shortened TTI using the DMRS received in the 1DMRS symbol (or the 1DMRS symbol and the additional DMRS symbol) included in the shortened TTI. The processing result is output to the control unit 301.

The reception signal processing unit 304 may be configured by a signal processor, a signal processing circuit or a signal processing device, and a measuring device, a measurement circuit or a measuring device, which are described based on common recognition in the technical field according to the present invention. it can.

<User terminal>
FIG. 18 is a diagram showing an example of the overall configuration of the user terminal according to the present embodiment. The user terminal 20 includes a plurality of transmission / reception antennas 201 for MIMO transmission, an amplifier unit 202, a transmission / reception unit 203, a baseband signal processing unit 204, and an application unit 205.

The radio frequency signals received by the plurality of transmission / reception antennas 201 are each amplified by the amplifier unit 202. Each transmitting / receiving unit 203 receives the downlink signal amplified by the amplifier unit 202. The transmission / reception unit 203 converts the frequency of the received signal into a baseband signal and outputs it to the baseband signal processing unit 204.

The baseband signal processing unit 204 performs FFT processing, error correction decoding, retransmission control reception processing, and the like on the input baseband signal. Downlink data (user data) is transferred to the application unit 205. The application unit 205 performs processing related to layers higher than the physical layer and the MAC layer. In addition, broadcast information in the downlink data is also transferred to the application unit 205.

On the other hand, the uplink data is input from the application unit 205 to the baseband signal processing unit 204. The baseband signal processing unit 204 performs retransmission control transmission processing (for example, HARQ transmission processing), channel coding, rate matching, puncturing, discrete Fourier transform (DFT) processing, IFFT processing, and the like. Are transferred to each transmitting / receiving unit 203. Also for UCI, channel coding, rate matching, puncturing, DFT processing, IFFT processing, and the like are performed and transferred to each transmitting / receiving section 203.

The transmission / reception unit 203 converts the baseband signal output from the baseband signal processing unit 204 into a radio frequency band and transmits it. The radio frequency signal frequency-converted by the transmission / reception unit 203 is amplified by the amplifier unit 202 and transmitted from the transmission / reception antenna 201.

Also, the transmission / reception unit 203 transmits the PUSCH in a shortened TTI (second TTI) configured with a smaller number of symbols than the normal TTI (first TTI). The PUSCH may include uplink data (first mode), both uplink data and UCI (second mode), or UCI (first mode). 3 embodiment).

In addition, when the shortened TTI is set so as to include one of 2 DMRS symbols from which the DMRS (demodulation reference signal) of the normal TTI PUSCH is received, the transmission / reception section 203 uses the 1 DMRS symbol for the PUSCH of the shortened TTI. Send DMRS. Further, when an additional DMRS symbol is set in the shortened TTI, the transmission / reception unit 203 may transmit the DMRS of the shortened TTI using the additional DMRS symbol.

The transmission / reception unit 203 can be a transmitter / receiver, a transmission / reception circuit, or a transmission / reception device described based on common recognition in the technical field according to the present invention. Further, the transmission / reception unit 203 may be configured as an integral transmission / reception unit, or may be configured from a transmission unit and a reception unit.

FIG. 19 is a diagram illustrating an example of a functional configuration of the user terminal according to the present embodiment. Note that FIG. 19 mainly shows functional blocks of characteristic portions in the present embodiment, and the user terminal 20 also has other functional blocks necessary for wireless communication. As shown in FIG. 19, the baseband signal processing unit 204 included in the user terminal 20 includes a control unit 401, a transmission signal generation unit 402, a mapping unit 403, a reception signal processing unit 404, and a measurement unit 405. I have.

The control unit 401 controls the entire user terminal 20. The control unit 401 controls, for example, signal generation by the transmission signal generation unit 402, signal mapping by the mapping unit 403, and signal reception processing by the reception signal processing unit 404.

Further, the control unit 401 controls a transmission time interval (TTI) used for receiving a downlink (DL) signal and / or transmitting an uplink (UL) signal. The control unit 301 sets a normal TTI of 1 ms or / and a shortened TTI shorter than the normal TTI. The configuration example and setting example of the shortened TTI are as described with reference to FIGS. The control unit 401 is based on an explicit notification from the radio base station 10 (1) an implicit notification or at least one of (2) RRC signaling, (3) MAC signaling, and (4) PHY signaling. The shortened TTI may be set (detected).

Specifically, the control unit 401 sets the shortened TTI (second TTI) so as to include one of the 2DMRS symbols in which the PUSCH DMRS in the normal TTI (first TTI) is transmitted (FIGS. 5, 10, 11 and 11). 14). In addition, the control unit 401 controls the transmission signal generation unit 402 so as to transmit the DMRS in the shortened TTI using the 1DMRS symbol (or the 1DMRS symbol and the additional DMRS symbol).

For example, when a plurality of shortened TTIs include the 1DMRS symbol, the control unit 401 multiplexes and transmits the plurality of shortened TTI demodulation reference signals in the 1DMRS symbol. That is, the control unit 401 multiplexes a DMRS of a shortened TTI and a DMRS of another shortened TTI among the plurality of shortened TTIs, and transmits the multiplexed DMRS in the 1 DMRS symbol. For the multiplexing, cyclic shift and / or Comb can be used.

When the same user terminal 20 transmits a PUSCH in the plurality of shortened TTIs, and when different resource blocks can be allocated to the PUSCH (FIG. 7A), the control unit 401 uses each of the plurality of shortened TTIs. A PRB that transmits DMRS is determined based on the assigned PRB. The control unit 401 may control the transmission signal generation unit 402 so as to transmit DMRS of any one of the plurality of shortened TTIs (for example, the earliest shortened TTI) using the determined PRB.

In addition, when the same user terminal 20 transmits a PUSCH in the plurality of shortened TTIs, and when it is not possible to assign different resource blocks to the PUSCH (FIG. 7B), the control unit 401 has the plurality of shortened TTIs. The PRB assigned by any one (for example, the earliest shortened TTI) is determined as the PRB that transmits the DMRS. The control unit 401 may control the transmission signal generation unit 402 so as to transmit DMRS of any one of the plurality of shortened TTIs (for example, the earliest shortened TTI) using the determined PRB.

Further, when different user terminals 20 transmit PUSCHs in the plurality of shortened TTIs, and when different resource blocks can be allocated to the PUSCHs (FIG. 8A), the control unit 401 uses the Comb to The DMRS of the shortened TTI may be multiplexed on the 1 DMRS symbol. Specifically, the control unit 401 controls the transmission signal generation unit 402 to transmit the DMRS of the shortened TTI using a Comb index different from that of the other user terminals 20. The Comb index may be indicated in a predetermined field of DCI, or may be determined in advance according to sTTI.

In addition, when different user terminals 20 transmit PUSCHs in the plurality of shortened TTIs and when it is not possible to assign different resource blocks to the PUSCHs (FIG. 8B), the control unit 401 uses the cyclic shift to The DMRS of the shortened TTI may be multiplexed on the 1 DMRS symbol. Specifically, the control unit 401 controls the transmission signal generation unit 402 to transmit the DMRS of the shortened TTI using a CS index different from that of the other user terminals 20. It should be noted that which CS index is used may be indicated by a predetermined field (for example, CS / OCC field) of DCI.

The control unit 401 can be configured by a controller, a control circuit, or a control device described based on common recognition in the technical field according to the present invention.

Based on an instruction from the control unit 401, the transmission signal generation unit 402 generates an uplink signal (including an uplink data signal and an uplink control signal) (for example, encoding, rate matching, puncturing, modulation, etc.) and performs mapping. Output to the unit 403. For example, the transmission signal generation unit 402 generates PUSCH including uplink data, PUSCH including uplink data and UCI (at least one of HARQ-ACK, CQI / PMI, and RI), and PUSCH including UCI.

Specifically, when the same user terminal 20 transmits a PUSCH in the plurality of shortened TTIs (FIGS. 7A and 7B), the transmission signal generation unit 402 uses any one of the shortened TTIs (for example, the earliest shortened TTI). A DMRS is generated using a CS index and / or OCC indicated by DCI.

In addition, when different user terminals 20 transmit PUSCHs in the plurality of shortened TTIs (FIGS. 8A and 8B), the transmission signal generation unit 402 transmits the CS index indicated by DCI with the shortened TTIs transmitted by the user terminals 20 and / or Alternatively, DMRS is generated using OCC.

Further, the transmission signal generation unit 402 may generate the DMRS transmitted by the additional DMRS symbol using a DMRS sequence of a group (DMRS sequence index) different from the DMRS transmitted by the 1 DMRS symbol.

The transmission signal generation unit 402 can be a signal generator, a signal generation circuit, or a signal generation device described based on common recognition in the technical field according to the present invention.

Based on an instruction from the control unit 401, the mapping unit 403 maps the UL signal (uplink control signal and / or uplink data signal) generated by the transmission signal generation unit 402 to a radio resource and outputs the radio signal to the transmission / reception unit 203. To do.

Specifically, the mapping unit 403 maps the DMRS generated by the transmission signal generation unit 402 to the PRB determined by the control unit 401 in the 1 DMRS symbol (or including the additional DMRS symbol). The mapping unit 403 may be a mapper, a mapping circuit, or a mapping device described based on common recognition in the technical field according to the present invention.

The reception signal processing unit 404 performs reception processing (for example, demapping, demodulation, decoding, etc.) on downlink signals (including downlink control signals and downlink data signals). The reception signal processing unit 404 outputs information received from the radio base station 10 to the control unit 401. The received signal processing unit 404 outputs, for example, broadcast information, system information, control information by higher layer signaling such as RRC signaling, DCI, and the like to the control unit 401.

The received signal processing unit 404 can be configured by a signal processor, a signal processing circuit, or a signal processing device described based on common recognition in the technical field according to the present invention. Further, the reception signal processing unit 404 can constitute a reception unit according to the present invention.

The measurement unit 405 measures the channel state based on a reference signal (for example, CSI-RS) from the radio base station 10 and outputs the measurement result to the control unit 401. Note that the channel state measurement may be performed for each CC.

The measuring unit 405 can be composed of a signal processor, a signal processing circuit or a signal processing device, and a measuring device, a measurement circuit or a measuring device which are explained based on common recognition in the technical field according to the present invention.

(Hardware configuration)
In addition, the block diagram used for description of the said embodiment has shown the block of the functional unit. These functional blocks (components) are realized by any combination of hardware and / or software. Further, the means for realizing each functional block is not particularly limited. That is, each functional block may be realized by one physically coupled device, or may be realized by two or more physically separated devices connected by wire or wirelessly and by a plurality of these devices. Good.

For example, the radio base station, user terminal, and the like in this embodiment may function as a computer that performs processing of the radio communication method of the present invention. FIG. 20 is a diagram illustrating an example of the hardware configuration of the radio base station and the user terminal according to the present embodiment. The wireless base station 10 and the user terminal 20 described above may be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, and the like. Good.

In the following description, the term “apparatus” can be read as a circuit, a device, a unit, or the like. The hardware configurations of the radio base station 10 and the user terminal 20 may be configured to include one or a plurality of each device illustrated in the figure, or may be configured not to include some devices.

Each function in the radio base station 10 and the user terminal 20 is obtained by reading predetermined software (program) on hardware such as the processor 1001 and the memory 1002, so that the processor 1001 performs computation, and communication by the communication device 1004, This is realized by controlling reading and / or writing of data in the memory 1002 and the storage 1003.

The processor 1001 controls the entire computer by operating an operating system, for example. The processor 1001 may be configured by a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic device, a register, and the like. For example, the baseband signal processing unit 104 (204) and the call processing unit 105 described above may be realized by the processor 1001.

Further, the processor 1001 reads programs (program codes), software modules, and data from the storage 1003 and / or the communication device 1004 to the memory 1002, and executes various processes according to these. As the program, a program that causes a computer to execute at least a part of the operations described in the above embodiments is used. For example, the control unit 401 of the user terminal 20 may be realized by a control program stored in the memory 1002 and operated by the processor 1001, and may be realized similarly for other functional blocks.

The memory 1002 is a computer-readable recording medium, and may be configured by at least one of ROM (Read Only Memory), EPROM (Erasable Programmable ROM), RAM (Random Access Memory), and the like, for example. The memory 1002 may be called a register, a cache, a main memory (main storage device), or the like. The memory 1002 can store a program (program code), a software module, and the like that can be executed to implement the wireless communication method according to the present embodiment.

The storage 1003 is a computer-readable recording medium, and may be composed of at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk, and a flash memory, for example. . The storage 1003 may be referred to as an auxiliary storage device.

The communication device 1004 is hardware (transmission / reception device) for performing communication between computers via a wired and / or wireless network, and is also referred to as a network device, a network controller, a network card, a communication module, or the like. For example, the transmission / reception antenna 101 (201), the amplifier unit 102 (202), the transmission / reception unit 103 (203), the transmission path interface 106, and the like described above may be realized by the communication device 1004.

The input device 1005 is an input device (for example, a keyboard, a mouse, etc.) that accepts external input. The output device 1006 is an output device (for example, a display, a speaker, etc.) that performs output to the outside. The input device 1005 and the output device 1006 may have an integrated configuration (for example, a touch panel).

Also, each device such as the processor 1001 and the memory 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured with a single bus or may be configured with different buses between apparatuses.

The radio base station 10 and the user terminal 20 may include hardware such as a microprocessor, an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array). A part or all of each functional block may be realized by the hardware. For example, the processor 1001 may be implemented by at least one of these hardware.

Note that the terms described in this specification and / or terms necessary for understanding this specification may be replaced with terms having the same or similar meaning. For example, the channel and / or symbol may be a signal (signaling). The signal may be a message. In addition, a component carrier (CC) may be called a cell, a frequency carrier, a carrier frequency, or the like.

Also, the radio frame may be configured with one or a plurality of periods (frames) in the time domain. Each of the one or more periods (frames) constituting the radio frame may be referred to as a subframe. Further, a subframe may be composed of one or more slots in the time domain. Further, a slot may be composed of one or more symbols (OFDM symbols, SC-FDMA symbols, etc.) in the time domain.

The radio frame, subframe, slot, and symbol all represent a time unit when transmitting a signal. Different names may be used for the radio frame, the subframe, the slot, and the symbol. For example, one subframe may be referred to as a transmission time interval (TTI), a plurality of consecutive subframes may be referred to as a TTI, and one slot may be referred to as a TTI. That is, the subframe or TTI may be a subframe (1 ms) in the existing LTE, a period shorter than 1 ms (for example, 1-13 symbols), or a period longer than 1 ms. Also good.

Here, TTI means, for example, a minimum time unit for scheduling in wireless communication. For example, in the LTE system, a radio base station performs scheduling to allocate radio resources (frequency bandwidth, transmission power, etc. that can be used in each user terminal) to each user terminal in units of TTI. The definition of TTI is not limited to this.

A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or a plurality of continuous subcarriers (subcarriers) in the frequency domain. Further, the RB may include one or a plurality of symbols in the time domain, and may have a length of one slot, one subframe, or 1 TTI. One TTI and one subframe may each be composed of one or a plurality of resource blocks. The RB may be called a physical resource block (PRB: Physical RB), a PRB pair, an RB pair, or the like.

Also, the resource block may be composed of one or a plurality of resource elements (RE: Resource Element). For example, 1RE may be a radio resource region of 1 subcarrier and 1 symbol.

Note that the structure of the above-described radio frame, subframe, slot, symbol, and the like is merely an example. For example, the number of subframes included in the radio frame, the number of slots included in the subframe, the number of symbols and RBs included in the slot, the number of subcarriers included in the RB, and the number of symbols in the TTI, the symbol length, The configuration such as the cyclic prefix (CP) length can be variously changed.

In addition, information, parameters, and the like described in this specification may be represented by absolute values, may be represented by relative values from a predetermined value, or may be represented by other corresponding information. . For example, the radio resource may be indicated by a predetermined index.

The information, signals, etc. described herein may be represented using any of a variety of different technologies. For example, data, commands, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description are voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, light fields or photons, or any of these May be represented by a combination of

Also, software, instructions, information, etc. may be transmitted / received via a transmission medium. For example, software may use websites, servers, or other devices using wired technology (coaxial cable, fiber optic cable, twisted pair and digital subscriber line (DSL), etc.) and / or wireless technology (infrared, microwave, etc.) When transmitted from a remote source, these wired and / or wireless technologies are included within the definition of transmission media.

Also, the radio base station in this specification may be read by the user terminal. For example, each aspect / embodiment of the present invention may be applied to a configuration in which communication between a radio base station and a user terminal is replaced with communication between a plurality of user terminals (D2D: Device-to-Device). In this case, the user terminal 20 may have a function that the wireless base station 10 has. In addition, words such as “up” and “down” may be read as “side”. For example, the uplink channel may be read as a side channel.

Similarly, a user terminal in this specification may be read by a radio base station. In this case, the wireless base station 10 may have a function that the user terminal 20 has.

Each aspect / embodiment described in this specification may be used alone, in combination, or may be switched according to execution. In addition, notification of predetermined information (for example, notification of being “X”) is not limited to explicitly performed, but is performed implicitly (for example, by not performing notification of the predetermined information). May be.

The notification of information is not limited to the aspect / embodiment described in this specification, and may be performed by other methods. For example, notification of information includes physical layer signaling (eg, DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (eg, RRC (Radio Resource Control) signaling, broadcast information (MIB (Master Information Block)). ), SIB (System Information Block), etc.), MAC (Medium Access Control) signaling), other signals, or a combination thereof. Further, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC connection setup (RRCConnectionSetup) message, an RRC connection reconfiguration (RRCConnectionReconfiguration) message, or the like. The MAC signaling may be notified by, for example, a MAC control element (MAC CE (Control Element)).

Each aspect / embodiment described herein includes LTE (Long Term Evolution), LTE-A (LTE-Advanced), LTE-B (LTE-Beyond), SUPER 3G, IMT-Advanced, 4G (4th generation mobile). communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), New-RAT (Radio Access Technology), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)) ), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth (registered trademark), systems using other appropriate systems and / or extended based on these It may be applied to the next generation system.

The processing procedures, sequences, flowcharts and the like of each aspect / embodiment described in this specification may be switched in order as long as there is no contradiction. For example, the methods described herein present the elements of the various steps in an exemplary order and are not limited to the specific order presented.

Although the present invention has been described in detail above, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments described herein. For example, the above-described embodiments may be used alone or in combination. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

This application is based on Japanese Patent Application No. 2015-255029 filed on Dec. 25, 2015. All this content is included here.

Claims (10)

A transmitter that transmits an uplink shared channel in a second TTI configured with a smaller number of symbols than the first transmission time interval (TTI);
A control unit that controls transmission of the uplink shared channel,
The control unit sets the second TTI to include one of two symbols to which the demodulation reference signal for the uplink shared channel of the first TTI is transmitted, and demodulates the uplink shared channel of the second TTI with the one symbol. A user terminal that transmits a reference signal for use. 2. When the plurality of second TTIs include the one symbol, the control unit multiplexes and transmits an uplink shared channel demodulation reference signal in the plurality of second TTIs within the one symbol. The user terminal described in 1. When the same user terminal transmits an uplink shared channel in the plurality of second TTIs, and when different resource blocks can be allocated to the uplink shared channel, the control unit allocates each of the plurality of second TTIs. The user terminal according to claim 2, wherein a demodulation reference signal of any one of the plurality of second TTIs is transmitted within the one symbol using a resource block determined based on a resource block to be determined. When the same user terminal transmits an uplink shared channel in the plurality of second TTIs, and when a different resource block cannot be allocated to the uplink shared channel, the control unit is the most out of the plurality of second TTIs. 3. The user terminal according to claim 2, wherein a demodulation reference signal of any of the plurality of second TTIs is transmitted within the one symbol using a resource block allocated in an early second TTI. When different user terminals transmit uplink shared channels in the plurality of second TTIs, and when different resource blocks can be allocated to the uplink shared channels, the control unit uses the plurality of second TTIs using Comb. The user terminal according to claim 2, wherein the demodulation reference signal is multiplexed within the first symbol. When different user terminals transmit uplink shared channels in the plurality of second TTIs, and when different resource blocks cannot be allocated to the uplink shared channels, the control unit uses the cyclic shift to perform the plurality of second TTIs. The user terminal according to claim 2, wherein the demodulation reference signal is multiplexed within the first symbol. The user terminal according to any one of claims 1 to 6, wherein the control unit transmits the reference signal for demodulation of the second TTI using another symbol included in the second TTI. The control unit maps uplink control information in the second TTI using the same rule as uplink control information mapped in the first TTI. The user terminal described in 1. A receiving unit that receives an uplink shared channel in a second TTI configured with a number of symbols smaller than a first transmission time interval (TTI);
A control unit for controlling reception of the uplink shared channel,
The control unit sets the second TTI to include one of two symbols from which the demodulation reference signal of the uplink shared channel of the first TTI is received, and uses the demodulation reference signal received by the one symbol Then, the radio base station demodulates the second TTI uplink shared channel. A wireless communication method using a second TTI configured with a smaller number of symbols than a first transmission time interval (TTI), in a user terminal,
Setting the second TTI to include one of two symbols to which a demodulation reference signal of the uplink shared channel of the first TTI is transmitted;
And a step of transmitting an uplink shared channel in the second TTI and transmitting a demodulation reference signal of the uplink shared channel of the second TTI with the one symbol.

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